A device for attaching an implement to a lifting unit is described in U.S. Pat. No. 5,466,113. This device has a bar that can be manually displaced between a locking position in which it holds the implement on the lifting unit and an unlocking position in which the bar releases the implement. It is proposed to displace the bar into the unlocking position by means of an electric or hydraulic actuator. A bar for attaching an implement can also be displaced by an externally activated actuator in other known lifting units.
If an actuator of this type is used for displacing the bar in a remote-controlled fashion, it is no longer possible to manually displace the bar because in this case it would also be required to manually move the actuator that is rigidly coupled to the bar.